A swallow has surprised ornithologists by surviving the coldest snap in the south west of England for 20 years.

Most swallows migrate to southern Africa during the autumn and the few that remain normally perish as the winter sets in.

But a swallow at the Marazion Marsh nature reserve near Penzance, Cornwall, has survived last week's severe cold spell when temperatures in the area, which normally has a mild climate, dipped to 19.4F (-7C).

Sightings of seven swallows have been reported in the UK this winter - four in Cornwall and three in Pembrokeshire - but the other six were found dead.

David Flumm, of the Royal Society for the Protection of Birds, which runs the reserve, said: "In a very mild winter it is possible for a swallow to survive in this country, but it is amazing that this one has lasted so long."

The story of survival came as forecasters warned that last week's freezing conditions could now be followed by 80mph gales this weekend.

Western coastal areas were expected to be worst affected but towns and cities inland could see winds of up to 50mph. Rain on Saturday was also forecast.

The swallow at Marazion Marsh is thought to have lost nearly half its body weight, as it has not been able to feed with any regularity.

Mr Flumm said: "We had four swallows wintering here but we have only seen a single bird recently."

Swallows rely on flying insects for food, but none were seen during the cold snap.

The bird was last seen on Friday but as the weather has been milder, there was no reason to believe it was not still hawking for insects, the RSPB said.

Alex McKechnie, (corr) a bird-watcher, who photographed the swallow on Friday said: "It looked as if it was sticking to the sunny spots in an attempt to stay warm."